Dry shaver construction

ABSTRACT

A dry shaver has an oscillatable shear unit and a drive connected with the unit for oscillating it, the drive being composed of at least one body having a plurality of bi-laminar oscillatory elements of ferro-electric ceramic material which are electrically and mechanically connected in parallel.

United States Patent 1191 Coharg et a1. [4 Aug. 7, 1973 DRY SHAVERCONSTRUCTION [75] Inventors: Christian Cobarg, Steinbach; Erich [56]References Cited Fenner, Gauting; Max UNITED STATES PATENTS Gumersdme'Munich; Walt" 2,325,238 7/1943 Flint 310/81; x yv g, Neukeferloh; Franzm, 2,373,431 4 1945 Sykes 310/8.1 x Munich; Rudolf Schiifer, Ebersberg;3,409,377 11/1968 Rogallo 310/80 X l-lelmut Thomann, Munich, all of3,509,626 /1970 Mead 30/45 Germany 3,631,595 1/1972 Scott 4. 30/45Asslgnee: EZZILQ Frankfurt (Mam) Primary Examiner-O1hcll M. Simpson yAssistant Examiner-Gary L. Smith [22] Filed: Sept. 9, 1971Attorney-Michael S. Striker [21] A 1.No.: 179 066 pp 57 ABSTRACT A dryshaver has an oscillatablc shear unit and a drive Foreign AppucafionPriority Data connected with the unit for oscillating it, the driveSept. 11, 1970 Germany P 45 152.9 being composed of at least one bodyhaving a plurality of bi-laminar oscillatory elements of ferro-electriccc- 521 u.s. c1 /439, 30/4302, 30/45 ramic material which areelectrically and mechanically [51] Int. Cl B26b 19/12, B26b 19/02connected in parangL [58] Field of Search 30/437, 43.8, 43.9,

20 Claims, 15 Drawing Figures PAIENIHJ AUG 71973 SHEET 6 OF 5 PATENTEU3.750.279

SHEET 5 OF 5 Fig. 9 81 Fig. 6

DRY SHAVER CONSTRUCTION BACKGROUND OF THE INVENTION The presentinvention relates generally to dry shavers, and more particularly to animproved dry shaver construction with a novel drive for the oscillatoryshear unit of the shaver.

Dry shavers are of course already known in a great variety of differenttypes and constructions. Generally speaking, however, the shear systemof dry shavers utilizes an upper shear section which is usuallystationary and provided with slots or openings and is most frequentlyknown as a shear foil or a similar element. Located beneath this uppersection is a lower section provided with cutter blades or the like whichis either oscillated or reciprocated linearly or is given rotaryoscillatory movement, in the former case the movement being along itslongitudinal axis and in the latter case the movement being about itslongitudinal axis. The two sections are spring-biased against oneanother so that, as the cutting edges on the cutter blades or the likeof the lower section move over the inner surface of the upper section orshear foil past the slots or openings therein, they will sever any ahirwhich extends through them. Frequently such dry shavers are alsoprovided with a trimming arrangement in form of two long rows of teethprovided on the upper and lower section respectively and cooperatingwith one another to trim longer hairs, for instance the hair at thetemples, as opposed to the short beard stubble.

The dry shavers known from the prior art mostly are constructed with anelectromagnetic oscillating armature and are intended to receive theirelectrical energy from a source of alternating current, usually being soconstructed that they can be readily switched over for use either with asource supplying llO-l25 volts or 220-250 volts. The armature oscillateswith reference to an electromagnet which is fixedly mounted in thehousing of the shaver and, together with one or more springs providedfor this purpose, it constitutes a mechanical oscillator whichoscillates at double the frequency of the alternating current source andwhich is connected with the lower section of the shear system by a swingarm as motion-transmitting element.

It is not surprising when it is pointed out that although this type ofdrive is relatively effective, it also is relatively bulky and heavy,particularly with reference to the overall weight of the othercomponents of a conventional dry shaver.'ln addition the volume of soundgenerated by such a drive, and the vibrations resulting from itsoperation, are such as to be frequently found objectionable by the user.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to overcome the aforementioned disadvantages of theprior art.

More particularly it is an object of the present invention to provide animproved dry shaver construction which is not possessed of thesediadvantages.

A concomitant object of the invention is to provide such a dry shaverconstruction which utilizes different principles than those known fromthe prior art for converting electrical energy into mechanical work.

Another object of the invention is to provide such a dry shaverconstruction in which the drive for the shear system is smaller, lighterin weight, quieter and provides fewer vibrations or vibrations of a lessobjectionable character than what is known from the art.

In pursuance of the above objects, and of others which will becomeapparent hereafter, one feature of the invention resides in a dry shaverwhich, briefly stated, comprises an oscillatable shear unit and drivemeans connected in motion-transmitting relationship with the shear unitand including at least one body which comprises a plurality ofbi-laminar oscillatory elements of ferro-electric ceramic materialconnected electrically and mechanically in parallel with one another. i

The novel drive according to the present invention is based upon autilization of the reverse piezo effect known as electrostriction tothose skilled in the art. There are now available ferro-electric ceramicmaterials such as barium titanate, lead zirconate titanate and the like,which permit-having with respect to conventional or classical piezocrystals a need for an excitation current which is lower by two decimalpowers than in such conventional crystals-the construction ofoscillatory motors of small output but usable effectiveness. It is ofparticular advantage that in constructions using such materials themechanical fundamental frequency can be coordinated with the frequencyof the alternating current with which the motor is supplied.

It is already known to produce from ferro-electric ceramic materialsso-called flexible oscillators by fixedly connecting two thinelectrode-carrying ceramic strips with one another and to fix them atone side or at two sides. Such elements are known as bi-laminar flexibleoscillators and their mechanical resistance and permanent bendingstrength can be improved by incorporating between the ceramic strips anapproximately equally thick metal strip which may also be constructed asa coupling element, depending on the use to which the respective elementis to be put. It is a characteristic of these bi-laminar flexibleoscillating elements, hereafter for the sake of convenience identifiedas oscillating elements", that they are electrically polarized in thedirection of their thickness. This means that the frequency of theexcited mechanical oscillation is that of the excitation current appliedto the electrodes, not double as is the case in electromagneticoscillatory armature motors or magnetostrictive oscillators.

However, it has been found that oscillating elements of the type hereunder discussion cannot be used per se as oscillating drives for themovable components of a dry shaver shear unit. The reason is that theusable mechanical output of these oscillating elements is very smallbecause of the very low mechanical resonance frequency mentioned above.The invention overcomes this problem by connecting several of theoscillating elements in such a manner that the summation of the outputsof the elements provides the required characteristics and the elementstogether constitute the oscillatory body of a ferro-electric oscillatorydrive or motor.

The drive accordingto the present invention can be constructed invarious ways in accordance with different embodiments. it is possible tolocate the bi-laminar oscillatory elements adjacent one another withtheir ends -that is their opposite ends-being fixed in respectivemounting rails one of which is fixed in the housing of th dry shaver andthe other of which is connected with the movable component or section ofthe shear unit via a suitable motion-transmitting element. Thisembodiment is suitable. both for shear systems with a linearlyoscillating movable component and for shear systems with a movablecomponent which is mounted for rotary oscillation. In the first instancethe oscillatory members are arranged so that the major surfaces ofadjacent ones face one another in juxtaposed relationship, and theoscillatory body oscillates in its own plane in parallelogram-likemovements, and in the second instance the oscillating elements arearranged adjacent one another with their longitudinal edges facing andthe oscillatory body constitutes an oscillatory surface which laterallyoscillates out of its center or normal plane.

According to another embodiment the oscillating elements can be arrangedadjacent one another with their opposite ends being held in a framewhich in turn is mounted in the housing of the dry shaver, whereas theiroscillating portions are connected with one another and coupled with themovable component of the shear system via a motion-transmitting element.Such a construction is particularly suitable for shear systems having amovable component which is mounted for rotary oscillations.

The construction according to the present invention, as will beappreciated, is highly simple in structure Because of this it permitscompensation of the movable masses. in such a manner that the motor issubdivided for instance into two oscillating bodies whose individualoscillating elements are so polarized or electrically connected that theoscillating bodies will perform mutually opposite oscillatory movementswhen connected to alternating current. The oscillating bodies can becoupled jointly with a single movable component of the shear system, orthey can each be coupled with such a movable component with the movablecomponents being located in known manner coaxially or laterally adjacentone another.

If the dry shaver utilizes a shear system or unit having two mutuallylinearly oscillatable movable components, then according to a furtherconcept of the invention a single oscillating body can be utilized whoseoscillating elements are connected at their opposite ends withrespective rails which are fixed to them as already mentioned before. Inthis case, however, each rail is connected with one of the movablecomponents, preferably via an articulate or flexible motion-transmittingelement which serves for mounting the respective movable component. Theindividual oscillating elements are fixedly connected in thisconstruction to rails at their opposite ends with their maximumdeflection-- that is oscillatory movement out of their normal restposition-taking place in their middle region. This means that theoscillating body as a whole performs contraction oscillations withdouble the frequency of the applied alternating current, whichoscillations are directly transmitted to the movable components of theshear unit. In such a construction it may also be of advantage to employthe mass-compensation principle within the oscillatory motor itself insuch a manner that the oscillating elements are electrically soconnected -cithcr for the entire motor or in two separate groups-inalternating relationship that when alternating current is applied tothem they will perform mutuallyopposite oscillatory movements so thatthe mass center of the oscillatory motor remains at rest.

Oscillating motors of the type here under discussion will operateparticularly effectively if not only the center metal strip of eachoscillating element is fixedly connected to mounting rails or the like,but also its ceramic strips. This assures a maximum possible oscillatorydeflection as a result of the electrostrictive forces, also andparticularly at the location where the connection is effected. It mustbe pointed out, however, that this advantage is ordinarily counteractedby the increased stresses acting upon the ceramic material with aconcomitant danger or reduction of the permanent bending strength ofthis material. According to the invention this is avoided by providing agradual transition between the free length of the respective oscillatingelement and the location where it is fixedly secured. In a particularlyadvantageous manner from a point of view of manufacturing this isachieved by mounting the ends of the oscillating elements in theirrespective rails or other components by embedding them in castablcresin. A further simplification can be achieved if the rails oranalogous elements themselves are cast of castable resin in a form intowhich the ends of the oscillating elements are introduced so that theybecome embedded when the resin hardens.

Furthermore, the bending stresses at the locations where the oscillatingelements are fixedly connected can be further removed in a substantialmanner, if according to a particularly advantageous and preferredembodiment of the invention the polarization or excitation of theindividual oscillating elements-which are connected at opposite endswith their respective mounting rails or the like in fixed mannerisselected in mutually opposite relationship for each half located atopposite side of the middle of the respective oscillating element. Withsuch a construction the two halves of each oscillating element will,when being excited and operating, be deflected in mutually oppositedirections so that the oscillatory configuration of the oscillatingelement during each oscillating movement will resemble the letter S,whereas the ends of the two halves at least approximately maintain thedirection of their rest position. This construction has a better degreeof effectiveness than the constructions utilizing deflection in only onedirection.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. la shows in elevation a firstembodiment of an FIG. 5a illustrates components of another embodiment ofthe invention;

FIG. 5b illustrates the embodiment with the components of FIG. 5a shownin position; I

FIG. 6 is a fragmentary diagrammatic elevation of a further embodiment;

FIG. 7 is a fragmentary perspective detail view of another embodiment;

FIGS. 8a-8d illustrate diagrammatically an additional embodiment of theinvention; and

FIG. 9 is a view analogous to FIG. 6 illustrating still a furtherembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now firstly theembodiment illustrated in FIGS. Ia and lb it will be seen that we havethere shown an oscillating element of bi-laminar construction and ofalready known type. A metallic strip or tongue 1 has secured at oppositesides to it thin strips 2 of a ferro-electric ceramic material on whichmetallic electrodes 3 are secured whose thickness is just sufficient toobtain the necessary conductivity. Soldered to the electrodes 3 adjacentthe location where the element is fixedly secured, are connecting wireswhich are not illustrated because they are not believed necessary for anunderstanding of the invention and because it is desired to avoid makingthe illustration confusing.

The thickness of the member 1 and of the strips 2 is approximately equaland is selected between 0.1 and 0.3 mm. Preferably the choice is suchthat an individual oscillating element can be excited to an optimumextent by supplying between ll and I25-volts alternating current. Thismeans that if two of such elements are connected in series they requirefor their excitation 220 volts alternating current and a simpleadjustment makes it thus possible to operate an oscillating motorconstructed in this manner with voltages of 110-125 or 220-250 volts.

One end portion of the oscillating element is inserted into a recess ofa mounting element, for instance a mounting rail 4, and retained asshown in FIG. lb by being cast in place with a castable resin 5. Theresin provides for a fixed but not entirely inelastic connection whichis thus protected against breakage due' to the oscillation of theelement. The castable resin tends to move up slightly along theelectrode surfaces of the electrodes 3 above the point of connection, asindicated at 51, thereby in effect forming a support against kinking. At11 the strip or tongue 1 projects slightly be yond the ceramic strips 2and can there be connected for coupling with adjacent oscillatingelements or with a component which is to have motion imparted to it,depending upon the circumstances of a particular application. The twoceramic strips are polarized in the direction of their thickness andtheir directions of polarization are so selected that they can beelectrically operated in series.

When an alternating current is supplied to the electrodes 3, theoscillating element will oscillate in the same manner as a rod which isfixedly connected at one end; that is if will oscillate with itsmechanical inherent or natural resonance frequency. The resonancedepends upon the length and thickness of the ceramic strips essentially,and the characteristics of the materials used; advantageously it is soselected that the natural resonance frequency of the oscillating systemwill be between 2 and 10, preferably between 3 and 5 Herz (Hz) above theoperating frequency, that is normally above the net frequency ofalternating current of 50 or 60 Hz or cycles. In known manner it can beprecisely selected by changing the free length of the oscillatingelement.

In FIGS. 2a and 2b we have illustrated a further bilaminar oscillatingelement whose opposite ends are fixedly connected in mounting rails 4,4', respectively. Here the electrode covers onthc ceramic strips areinterrupted in the region of the symmetry line a-a, so that each ceramicstrip carries two electrodes 31 and 32. By exchanging the connectionswith the source of alternating current or by reversing the direction ofpolarization in the ceramic strips 2 on opposite sides of the symmetryline a-a, an S-shaped oscillatory deflection can be induced in thebi-laminar oscillating element 1, 2, with a point of reversal ofdirection in the region of the symmetry line a-a. It will be appreciatedthat the element in FIGS. 2a and 2b can also be considered assuming thatthe electrodes extend over the entire length of the strips rather thanbeing interruptedas a construction whose largest oscillatory deflectionoccurs in the region of the center line a. In that case the strip 1 mustbe provided in this region with a laterally projection portion 12 asshown in FIG. 2b so that the element can be coupled either with othersimilar ele' ments or with the component which is to have motiontransmitted to it.

Coming now to FIG. 3 it will be seen that this illustrates in a highlysimplified form a dry shaver having an apertured shear head. The housingis identified with reference numeral 21 and provided with a shear headframe 22 which can be disconnected from the housing and carries acylindrically curved shear foil 23 which is sieve-like, that isapertured in the manner of a sieve or screen. Located beneath the foil23, which is a stationary upper section or component of the shear unit,is a movable lower shear unit component 24 provided with cuttinglamellas 241 of arcuate configuration; the component 24 is to bereciprocated or oscillated to and fro in the direction of the doubleheaded arrow F and is lightly pressed by non-illustrated helical springsfrom below so that its cutting edges contact the underside of the shearfoil 23. The component 24 is readily releasably coupled with a pin orprojection 25.

The housing 21 further accommodates a ferroelectrical oscillatory motor26 composed of a package of bi-laminar oscillating elements I, 2, 3 ofthe type shown in either FIG. 1 or FIG. 2, which are mounted at oppositeends in two mounting rails 4, 4' with the major surfaces of adjacentones of the elements 1, 2, 3 being juxtaposed. The lower rail 4 isfixedly mounted in the housing 21 whereas the upper rail 4' carries thecoupling projection 25. The motor 26 oscillates at the net frequency.that is at the frequency of a current supplied to it. Reference numeal27 identifies a socket in the bottom of the housing 21 so that via asuitable electrical cord the motor 26 can be connected with a source ofalternating current.

In FIG. 4 we have illustrated an embodiment of the dry shaver in whichthe shear foil is identified with reference numeral 43, being held in aframe 42. Here, however, the component 24 is replaced by a substantiallysemi-cylindrical movable component 44 which is provided with elongatedcutter lamellas 441 and which performs rotary oscillatory movementsabout an axis 442 journalled in the end faces of the frame 42, in thedirection of the double-headed arrow G. A rib 443 is formed on theunderside of the component 44, being of downwardly open U-shaped crosssection.

The housing 41 in this case accommodates another ferro-electricoscillatory motor 46 composed of a packet of bi-laminar oscillatingelements 1, 2, 3, this time of the type shown in FIG. I and arranged ina common plane with their lower end portions being mounted in a rail 4.The portions 11 of the oscillating element here engage into the hollowof the U-shaped rib 443 so that, when the motor performs oscillatorymovements in the direction of the arrow H at the net frequency, that isthe frequency of the source of alternating current, the component 44will perform rotary oscillations about its axis 442.

In FIG. we have illustrated a frame 471 having approximately the widthof the movable component 44 and which is mounted in the housing 41' inparallelism with the base surface of the component 44. The frame 471carries mounted at opposite ends a plurality of bilaminar oscillatingelement 1, 2, 3 which oscillate in a common phase and whose centerportion, where the maximum oscillatory deflection occurs, are connectedvia a comb-shaped member 48 which is provided at its upper side with oneor more teeth 481. The member 48 in turn cooperates with a correspondingrow of teeth 444 at the underside of the component 44. It will beappreciated that, as shown in FIG. 5a, two or several of suchoscillating motors 47 can be arranged above one another and connected inparallel via their member 48, in order to obtain the necessary output.This embodiment is particularly suitable for producing a very lowprofileapparatus whose housing 41' has an exterior configuration resembling aprism with strongly rounded edges as suggested in FIG. 5b and which canbe readily gripped.

FIG. 6 is a diagrammatic illustration of the possibility of utilizingtwo or three mutually opposite oscillating movable components of theshear system, which are driven by an oscillating motor having acorresponding number of oscillating bodies. FIG. 6 shows a shear systemhaving a U-shaped comb-like member 63 provided with slots 631 and twoknife or blade-carrying members 64, and 64 which are also provided withslots 641. The members 64, and 64 are driven by oscillating bodies 26,and 26, respectively, of an oscillatory motor which is constructed inaccordance with FIG. 3; reference numeral designates the necessarycoupling projections. The direction of oscillatory movement of the twobodies 26, and 26 during the two half waves of the net frequency isanalogous to that indicated by the full-line and broken-line arrows,respectively which are shown in FIG. 8a. It should be pointed out thatif a motor has two oscillatory bodies the switchover from 110 to 220volts can be effected also by parallel or series connection of the twooscillatory bodies.

The embodiment in FIG. 7 is somewhat analogous to that of FIG. 4 but hasthree turnably journalled movable components 44,, 44,, and 44,, whichare mounted coaxially on the shaft 442 and of which the outer ones,identified with reference numeral 44, and 44,, together with theirrespectively associated oscillatory bodies 46, and 46,, haveapproximately the same oscillatory mass as the middle component 44 withits associated oscillatory body 46 Because of this constructionvibrations are completely compensated in this embodiment.

Coming now to FIG. 8 it will be seen that this illustrates aparticularly advantageous embodiment of an oscillating motor for thedrive of two movable components which oscillate linearly in mutuallyopposite directions at double the frequency of the motor. The twomovable components are identified with reference numerals 74, and 74 andare swingably mounted above the base plate 7 of the non-illustratedhousing with parallelogram linkages of articulated or springy rods 71,with only the outer ones 71, and 71., being illustrated to avoidconfusion. An oscillatory motor 76 is coupled with its mounting rails 4,and 4,, with these outer rods 71 and 71 and the bi-laminar oscillatingelements are connected at their opposite ends fixedly with therespective rails 4, and 4 The deflection of the oscillating element withthe latter, or rather the direction of deflection, is of no consequencein this motor so that by appropriately choosing the polarity betweenadjacent oscillating elements, or between two adjacent groups of suchelements, the oscillation can be made in mutually opposite directions sothat the mass forces within the motor are compensated for as indicatedin FIG. 8c.

It is advantageous to tune the oscillating system with at least onespring 77 tensioned between the articulated rods to resonance, unlessthe rods themselves are configurated as springy rods and fixedly mountedin the base plate 7.

This particular embodiment has a further advantage, namely the fact thatthe oscillatory deflection of the motor 76 with respect to the height aof its coupling above the base plate 7 is transmitted in relationship tothe length of the rods 71, and that this relationship can be selected asdesired, so that the motor on the one hand and the shear system on theother hand can each be constructed for optimum advantage and becoordinated with one another.

It is also possible to modify the FIG. 8 embodiment by for instancereplacing the component 74 with a shear foil 23 longitudinally slidablyshiftably mounted in a frame 22 such as shown in FIG. 1, as long as anappropriate mass compensation is provided. In this case the component 74would extend over the entire length of the frame such as the component24 in FIG. I. In such a shear system both the foil and the cutter unit,that is the component 74,, will oscillate with respect to the housing.It is possible in such a construction to make the amplitude ofoscillations of the shear foil smaller and to keep it at a value such ashas been found advantageous in accordance with test results in order tobe able to better guide the beard stubble into the holes of the shearfoil than is'possible with a stationary shear foil which is movedmanually over the skin. It is also possible to modify FIG. 8 byproviding the arrangement shown in FIG. 3, if the motor 76 is coupledwith only one of the rods, for instance the rod 71, whereas 71 is a partof the housing 7 itself, namely a lateral wall thereof, as is suggestedin FIG. 8d.

The embodiment in FIG. 9, finally, illustrates how an oscillating motorcan be subdivided by providing it with two oscillating bodies 86, and86,, as is basically already disclosed in FIG. 6. This motor can drive asingle movable component of the shear system, such as the component 24of FIG. 3. Here, the packets of oscillating elements are connected atopposite ends again in mounting rails 4, 4 and are supported on a baseplate 81 at different heights in order to be above having them atidentical lengthto accommodate the transmission member 83 which couplesthe body 86 with the connecting rod 82 provided on the body 86,. The rod82 in turn is coupled with the component 24 via the transmission member25. The element 83 is a doublearmed lever which is pivotable about theaxis 84 and which serves for reversing the direction of movement of theoutput of the body 86, which oscillates in direction counter to theoscillation of the body 86,. The axis or shaft 84 is journalled in anon-illustrated fork mounted on the plate 81.

With this embodiment vibrations can be effectively compensated despitethe to and fro movement of component 24. The oppositely oscillatingmasses 24, 82, 86, on the one hand and 86 on the other hand, can be madeidentical by differential packet sizes of the two oscillating bodiesand/or by mounting a compensating weight at the upper rail 4' of theoscillating body 86 It will be appreciated that it is'possible in thisdisclosure to suggest only some of the many possibilities formodifications which will offer themselves to those skilled in the art.Motors of the type here under discussion and disclosed, that isoscillatory motors based upon the use of bi-laminar oscillating elementsof the type discussed, can be used in many applications, including theelectrical drive of other small devices having a low power requirementbesides dry shaves, and in which parts perform oscillatory orreciprocatory 'movements. This includes for instance devices used forhygienic and beauty purposes, such as electrical toothbrushes, massagingbrushes, vibrators, manicure devices and the like.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in adry shaver construction, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. In a dry shaver, in combination, an reciprocable shear unit; anddrive means connected in motiontransmitting relationship with said shearunit, said drive means including at least one body which comprises aplurality of electrically connected bi-laminar oscillatory' elements offerro-electric ceramic material which are mechanically connected inparallelism with one another. a

2'.- In a dry shaver as defined in claim 1; further comprising anarticulated resilient transmission element connecting said drive meansand shear unit in said monon-transmitting, relationship.

3. In a dry shaver as defined in claim 1, said bilaminar elements eachhaving opposite ends and being arranged laterally adjacent to but spacedfrom one another; further comprising a housing; and a pair of mountingrails each fast with said bi-laminar elements at one of said ends, oneof said rails being mounted in said housing and the other being coupledwith said shear unit.

4. In a dry shaver as defined in claim 3, said shear unit comprising anupper section and a reciprocating lower section; and wherein said drivemeans is connected with said lower section.

5. In a dry shaver as defined in claim 3, wherein said bi-laminarelements have major surfaces, and wherein the major surfaces of adjacentones of said bi-laminar elements are juxtaposed.

6. In a dry shaver as defined in claim 3, said drive means comprising acylindrically curved upper section and a lower section beneath saidupper section and mounted for rotary oscillation about the cylinder axisof said upper section; and wherein said bi-laminar elements haverespectively juxtaposed longitudinal edges and are arranged adjacent butspaced from one another.

7. In a dry shaver as defined in claim 6, wherein said bi-laminarelements are arranged in the plane of symmetry of said shear unit.

8. In a dry shaver as defined in claim], wherein said material is bariumtitanate.

9.. In a dry shaver as defined in claim I, wherein said material islead-zirconate-titanate.

10. In a dry shaver as defined in claim 1; further comprising a housingand a frame mounted in said housing; wherein said bi-laminar elementsare arranged adjacent but spaced from one another and have opposite endsfixed in said frame and oscillatory center portions, said drive meansfurther comprising coupling means coupling said center portions foroscillations in unison; and motion-transmitting means connecting saidcenter portions with said shear unit.

11. In a dry shaver as defined in claim 10, said shear unit having acylindrically curved upper section, and a lower section mounted forrotary oscillatory movement about the cylinder axis of said uppersection; and wherein said frame is mounted in parallel with saidcylinder axis and extends normal to the center plane of said shear unit.

12. In dry shaver as defined in claim 1, said shear unit comprising apair of shear sections, and said drive meanscomprising an additionalbody, each of said bodies being connected with one of said shearsections, and said bi-laminar elements of the respective bodies beingconnectable to alternating current and being polarized or electricallyconnected in such a'manner that said bodies oscillate in mutuallyopposite direction.

13. In a dry shaver as defined in claim 1, said shear unit having twoshear sections which are oscillatable in mutually opposite directions;said bi-laminar elements having opposite ends and being arrangedadjacent but spaced from one another; and further comprisng a pair ofmounting rails each fixedly connected with said hilaminar elements atone of said ends, each of said rails being coupled with amotion-transmitting member which engages a respective one of saidsections.

14. In a dry shaver as defined in claim I; further comprising at leastone additional similar body; said bodies being connected with said shearunit and the bi-Iaminar elements of one of said bodies performingoscillatory movements oppositely to those of the other of said bodies.

15. ln a dry shaver as defined in claim 1, said bilaminar elementshaving a resonance frequency of their basic oscillation which is between2 and Hz higher than the frequency of a source of alternating currentwith which said drive means is to be connected.

l6. ln a dry shaver as defined in claim 15, wherein said resonancefrequency is between 3 and 5 Hz higher than said frequency of saidsource.

17. In a dry shaver as defined in claim 3, wherein said bi-laminarelements each have two halves at opposite sides of a centerlineintemediate their opposite ends, and wherein each half oscillates indirection opposite the other half so that during oscillation eachbi-laminar element oscillates in a substantially S-shaped configuration.

18. In a dry shaver as defined in claim 3, said bilaminar elementshaving opposite ends and outer laminae of ceramic material; and whereinsaid rails also enther comprising a hardenahle resin in each slotretaining the respective end therein.

20. In a dry shaver as defined in claim 18, said rails being ofsynthetic plastic material, and said opposite ends each being embeddedin one of said rails.

1. In a dry shaver, in combination, an reciprocable shear unit; anddrive means connected in motion-transmitting relationship with saidshear unit, said drive means including at least one body which comprisesa plurality of electrically connected bilaminar oscillatory elements offerro-electric ceramic material which are mechanically connected inparallelism with one another.
 2. In a dry shaver as defined in claim 1;further comprising an articulated resilient transmission elementconnecting said drive means and shear unit in said motion-transmittingrelationship.
 3. In a dry shaver as defined in claim 1, said bi-laminarelements each having opposite ends and being arranged laterally adjacentto but spaced from one another; further comprising a housing; and a pairof mounting rails each fast with said bi-laminar elements at one of saidends, one of said rails being mounted in said housing and the otherbeing coupled with said shear unit.
 4. In a dry shaver as defined inclaim 3, said shear unit comprising an upper section and a reciprocatinglower section; and wherein said drive means is connected with said lowersection.
 5. In a dry shaver as defined in claim 3, wherein saidbi-laminar elements have major surfaces, and wherein the major surfacesof adjacent ones of said bi-laminar elements are juxtaposed.
 6. In a dryshaver as defined in claim 3, said drive means comprising acylindrically curved upper section and a lower section beneath saidupper section and mounted for rotary oscillation about the cylinder axisof said upper section; and wherein said bi-laminar elements haverespectively juxtaposed longitudinal edges and are arranged adjacent butspaced from one another.
 7. In a dry shaver as defined in claim 6,wherein said bi-laminar elements are arranged in the plane of symmetryof said shear unit.
 8. In a dry shaver as defined in claim 1, whereinsaid material is barium titanate.
 9. In a dry shaver as defined in claim1, wherein said material is lead-zirconate-titanate.
 10. In a dry shaveras defined in claim 1; further comprising a housing and a frame mountedin said housing; wherein said bi-laminar elements are arranged adjacentbut spaced from one another and have opposite ends fixed in said frameand oscillatory center portions, said drive means further comprisingcoupling means coupling said center portions for oscillations in unison;and motion-transmitting means connecting said center portions with saidshear unit.
 11. In a dry shaver as defined in claim 10, said shear unithaving a cylindrically curved upper section, and a lower section mountedfor rotary oscillatory movement about the cylinder axis of said uppersection; and wherein said frame is mounted in parallel with saidcylinder axis and extends normal to the center plane of said shear unit.12. In dry shaver as defined in claim 1, said shear unit comprising apair of shear sections, and said drive means comprising an additionalbody, each of said bodies being connected with one of said shearsections, and said bi-laminar elements of the respective bodies beingconnectable to alternating current and being polarized or electricallyconnected in such a manner that said bodies oscillate in mutuallyopposite direction.
 13. In a dry shaver as defined in claim 1, saidshear unit having two shear sections which are oscillatable in mutuallyopposite directions; said bi-laminar elements having opposite ends andbeing arranged adjacent but spaced from one another; and furthercomprising a pair of mounting rails each fixedly connected with saidbi-laminar elements at one of said ends, each of said rails beingcoupled with a motion-transmitting member which engages a respective oneof said sections.
 14. In a dry shaver as defined in claim 1; furthercomprising at least one additional similar body; said bodies beingconnected with said shear unit and the bi-laminar elements of one ofSaid bodies performing oscillatory movements oppositely to those of theother of said bodies.
 15. In a dry shaver as defined in claim 1, saidbi-laminar elements having a resonance frequency of their basicoscillation which is between 2 and 10 Hz higher than the frequency of asource of alternating current with which said drive means is to beconnected.
 16. In a dry shaver as defined in claim 15, wherein saidresonance frequency is between 3 and 5 Hz higher than said frequency ofsaid source.
 17. In a dry shaver as defined in claim 3, wherein saidbi-laminar elements each have two halves at opposite sides of acenterline intermediate their opposite ends, and wherein each halfoscillates in direction opposite the other half so that duringoscillation each bi-laminar element oscillates in a substantiallyS-shaped configuration.
 18. In a dry shaver as defined in claim 3, saidbi-laminar elements having opposite ends and outer laminae of ceramicmaterial; and wherein said rails also engage said outer laminae at leastat one of said opposite ends.
 19. In a dry shaver as defined in claim18, said rails being comb-shaped and slotted; and wherein said oppositeends are each received in one of said slots; and further comprising ahardenable resin in each slot retaining the respective end therein. 20.In a dry shaver as defined in claim 18, said rails being of syntheticplastic material, and said opposite ends each being embedded in one ofsaid rails.